1. Field of the Invention
This invention generally relates to integrated circuits, and more particularly to an integrated circuit package having an inductance loop formed from at least one input/output pin of the package.
2. Description of the Related Art
One perennial goal among circuit designers is to decrease the size of integrated circuits. This goal is largely driven by market demand for ever-smaller consumer electronics, communications devices, and display systems to mention a few. There are, however, a number of impediments that undermine this goal, one of which will now be discussed.
Many integrated circuits are not self-contained devices. To ensure proper operation, these circuits must therefore be connected to one or more external components through connections which do not involve the use of an IC package input/output pin. This is accomplished, for example, by connecting the integrated circuit chip 1 to an off-package component 2 using bonding wires 3, as shown in FIG. 1. The need to establish off-package connections increases the cost and complexity of the manufacturing process and therefore is considered highly undesirable.
The approach taken in U.S. Pat. No. 6,323,735 is undesirable for at least two reasons. First, in order to form the inductor loop completely within the IC package, the package substrate must be formed to include bonding pads separate from the input/output package pins. The need to form these special pads increases the cost and complexity of the manufacturing process. Second, in order to accommodate the bonding pads, the size of the integrated circuit substrate must be increased and as a result more circuit board space is consumed. These effects undermine the goal of increasing integration and miniaturization.
Another approach, disclosed in the text “Wireless CMOS Frequency Synthesizer Design,” by Craninckx, discloses a self-contained integrated circuit package containing an inductor loop. This loop is formed by connecting bonding wires between bonding pads on the IC chip and respective input/output pins of the IC package. The input/output pins are then connected by a third bonding wire. While this approach does not require the formation of special bonding pads on the package substrate, it is has at least two drawbacks that make it undesirable. First, like in the '735 patent, a bonding wire is used to connect the input/output pins. As previously noted, these wires are susceptible to damage during manufacture and/or use. Second, the input/output pins connected by the third bonding wire are located on opposite sides of the package. As a result, the third wire must pass over the IC chip. This is undesirable because the wire could short certain portions of the chip circuitry and introduce noise and other interfering influences which substantially degrade chip performance.
In view of the foregoing considerations, it is apparent that a need exists for an integrated circuit package which is more economical and requires fewer processing steps to manufacture than conventional IC packages, and which is also less susceptible to damage and noise which can degrade reliability and performance not only of the chip circuitry but also the host system of the chip. A need also exists for an integrated circuit package which is self-contained at least with respect to connection of an inductor loop connected to the chip, and which is able through this connection to achieve at least one of the aforementioned advantages.